The present invention relates to interconnect designs and assemblies for head gimbal assemblies and more particularly, to interconnect designs and assemblies which enable a micro electro mechanical system motor (micromotor) to be packaged into a head gimbal assembly.
Disc drives are well known in the art and comprise several discs, each disc having several concentric data tracks for storing data. There is a high demand for increased aerial density of discs, which results in an effort to increase both the number of tracks per inch (TPI) and the number of bits per inch (BPI) on the disc. As a result, there is likewise a demand for a high resolution microactuator to precisely position the head over a selected radial track of the disc. More particularly, as efforts continue to increase track density, the radial spacing between concentric data tracks on the disc decreases. Conventional actuator motors, such as voice coil motors, lack sufficient resolution to effectively accommodate high track-density discs, necessitating the addition of a high resolution head microactuator.
Various microactuator designs have been considered to accomplish high resolution head positioning, including piezoelectric, electromagnetic, electrostatic, capacitive, fluidic, and thermal actuators. Various locations for the microactuator have been suggested, including on the slider itself and at the head mounting block connecting the head suspension load beam to the actuator arm. Locating the microactuators at the head mounting block was not desirable because the microactuators could achieve only limited frequency response in micropositioning the head, due to the relatively large mass being moved by the microactuator motor. More promising are micromotors located on the slider. However, sliders having associated micromotors suffer from several shortcomings which limit their feasibility.
For example, many micromotors are fabricated independently of the slider and subsequently must be attached to the slider. Consequently, the micromotors require additional tooling and assembly steps to attach the micromotor to the slider. This increases the complexity of the manufacturing process and creates additional fabrication steps. Due to the fragile nature and small size of micromotors, it has been prohibitively expensive, or inefficient, or both to manufacture sliders having micromotors in any sort of volume.
Thus, there is a need in the art for a micromotor assembly process which allows micromotors to be incorporated into the slider assembly in high volume without being cost prohibitive.
The present invention is a package for incorporating a micromotor into a head gimbal assembly. The micromotor serves to allow the slider to be more precisely positioned over a selected data track on a disc. The micromotor is incorporated in the head gimbal assembly, and actuation of the micromotor requires that certain electrical connections be made to the micromotor. In addition, the micromotor must be attached to the head gimbal assembly by some form of mechanical connection.
A method of making the electrical and mechanical connections between the head gimbal assembly and a micromotor is through a process of using solder and reflow techniques. A micromotor is attached to a flex circuit, and solder bumps are applied to the surface of the micromotor. The slider is then placed onto the micromotor, and the combined flex circuit, micromotor, and slider are passed through a reflow oven allowing the solder bumps to create the necessary electrical and mechanical connections at solder joints formed between the micromotor, slider, and flex circuit.
Alternately, it is possible to make certain electrical connections by using wire bonding methods to connect the micromotor to a flex circuit. In yet another embodiment, a micromotor is fabricated with a via, which reduces the need for an electrical connection using either a wire bond or a flex circuit.